BOSTON (CBS) – Accusations that Democratic Congressman John Tierney knew about his family’s illegal gambling business appear to have taken a toll on his shot at re-election.

In a new poll taken for the Boston Globe by the University of New Hampshire Survey Center, Republican Richard Tisei leads Tierney in the Sixth District, 37-to-31 percent.

But, 30-percent of voters surveyed are still undecided.

Tierney is an eight-term congressman who has denied any knowledge that his brother-in-law ran an illegal offshore gambling company.

Tisei, a former state senator, ran unsuccessfully for lieutenant governor two years ago.

Massachusetts has not sent a Republican to the U.S. House of Representatives in 16 years.